The invention provides an environmental control apparatus, an environmental control system, an environmental control method, and an environmental control program that can create a sufficiently comfortable air environment in a room. An environmental control apparatus (10, 10a, 110, 110a, 210, 310) that is installed in a room and is portable, comprises a sensor unit (11. 211), a determination unit (12, 12a, 212), and an output unit (14, 213). The sensor unit senses the air environment of the room. The determination unit determines whether the air environment of the room is within the range of a comfort zone based on information about the air environment of the room. The output unit, based on at least the information about the determination result of the determination unit, outputs information or a signal in order to make the air environment of the room fall within the range of the comfort zone.